The compound 1,3,5-tri-methyl-2,4,6-tri-(3,5-di-tert-butyl-4-hydroxybenzyl) mesitylene is a commercial antioxidant (Ethanox.RTM.330, product of Ethyl Corporation). This compound and a method of preparing it by reacting 3,5-di-tert-butyl-4-hydroxybenzyl alcohol and mesitylene together with sulfuric acid or a Friedel Crafts catalyst is described in Rocklin et al. U.S. Pat. No. 3,026,264.
Another method for making the above antioxidant is described in Gurvich et al. GB No. 1,327,542. According to Gurvich et al., 2,6-di-tert-butyl-4-methoxymethyl phenol and mesitylene acid are mixed in an inert solvent such as methylene chloride and stirred at 1.degree.-5.degree. C. while adding sulfuric acid.
The present invention is an improvement on the process described by Gurvich et al. which results in a substantial cost reduction.